Safety switch for engine cooling systems



Nov. 28, 1950 F. w. MURPHY 2,532,182

SAFETY swrrcu FOR ENGINE coouuc; SYSTEMS Filed Oct. 11, 1948 2Sheets-Sheet 1 9 r r Z i ii 0 6 IN V EN TOR.

F. W. MURPHY SAFETY SWITCH FOR ENGINE COOLING SYSTEMS Nov. 28, 1950 2Sheets-Sheet 2 Filed Oct. 11, 1948 INVENTOR. g; WMw/rp'fiy 7'0. IGNITIONPatented Nov. 28, 1950 SAFETY SWITCH FOE ENGINE COOLING SYSTEMS Frank W.Murphy, Tulsa, Okla.

Application October 11, 1948, Serial No. 53,943

3 Claims.

This invention relates to a safety means for pumps or engines.

In the embodiment of the invention herein disclosed, the device isconstructed in the form of an attachment which can be secured to enginesor pumps and will permit the unattended operation thereof for statedperiods with the assurance that if the engine or pump should becomeoverheated it will be automatically stopped, and can be subsequentlystarted up again when the overheated condition has been corrected.

In the embodiment of this invention herein disclosed, a conventionaltemperature indicating meter employing a Bourdon tube, thermal ortemperature responsive bulb is modified to form a switch which is openwhen the operating temperature of the engine or pump is normal, but isclosed when the temperature is excessive, the switch being interposed inthe ignition system so that the ignition system will be grounded and theengine stopped.

A further object is to provide a safety cut-off switch adapted for gasor internal combustion engines having a vapor cooling system with acondensing radiator cooled by a fan driven from the engine by a belt andin which the cooling water around the engine jacket is maintained at theboiling point of water, namely 212 F. at all times and the hot vapor orsteam rising therefrom is condensed in the radiator instead of boilingaway and the condensation returns to the jacket for normal operation ofthe engine. However, failure of the cooling system caused by a brokenfan belt of the radiator cooling and condensing fan or leakage of waterbelow nor mal running level will not raise the temperature above 212 F.so that it is impossible to use a conventional temperature safetyswitch. Instead, the engine continues to run with the cyiinder wallgetting hotter, while the water jacket area gets cooler with lack ofvapors until the piston scores the cylinder walls and seizes causingserious damage.

With the present invention, the enginewill operate normally when thewater level ismaintained, and the water maintained around the Bourdontube to control the temperature indicator, and switch for cutting on orgroundingthe ignition system to stop the engine when exces sively hot,will not boil being maintained by its distance from the engine cylindersand sur-- rounding cooler ambient atmospheres sufi'iciently cool toprevent boiling or overheating. However, breaking of the fan belt causesthe vapors to crowd the radiator in which the vapors are normallycondensed to maintain the proper operating temperature at or below 212F., faster than it can condense them and slight pressure thus causedforces the water at such temperature to seek escape through a ventadjacent or above the Bourdon tube in such a manner that the escapinghot water acting on the tube causes the indicator pointer to move acrossthe dial indicating excessive heat and close the switch to cut oif theignition system as by grounding the magneto ignition circuit of theengine to stop the same until the defect is corrected and the engineagain started, to prevent damage. Also, should the water in the coolingsystem be lost or fall below normal level by leakage or otherwise, themoment the level falls too low below the Bourdon tube, the steam escapesfrom the overheated cooling system past or around the tube and operatesthe indicator hand and switch as described, thereby supplying adependable contrcl device for the safe operation of engines or pumps toprotect them from damage.

With the above and other objects in view, my invention consists in thearrangement, combination and details of construction disclosed in thedrawings and specification, and then more particularly pointed out inthe appended claims.

In the drawings, 7

Figure 1 is an elevation of an engine having ,-g a vapor cooling systemequipped with a safety switch or control system embodying the presentinvention,

Figure 2 is an enlarged sectional view of the operating and controlelement, taken on the line 2--2 of Figure 1,

Figure 3 is a detached perspective elevation partly broken away of thesafety switch or control device; and

Figure 4 is a diagrammatic view showing the manner of installing thedevice in the ignition system of an engine.

Referring to the drawings in detail, It desig nates a conventional gasor internal combustion engine or pump having the usual vapor coolingsystem including a water jacket H around the cylinder through which thewater is circulated by a conventional pump 92 ,or from which the hotvapors or steam rising from the jacket is circulated or passed into acondenser or radiator l3 having the usual cores, .to be cooledandcondensed by a cooling fan driven inthe usual manner from the engine,as by a fan belt (not shown) as is customary. In a vapor cooling system,the cooling water in the jacket around the motor or cylinders thereof ismaintained at a tempera- 3 ture of 212 F. at all times during the normalrunning of the engine. It is impossible to use a conventionaltemperature safety switch to stop the engine because failure of thecooling system caused by inoperation of the cooling fan as by a brokenfan belt of the radiator or condenser, or leakage of the water will notraise the temperature above 212 to operate the switch and stop theengine as the engine will continue to run with the cylinder wall gettinghotter while the water jacket area gets cooler with lack of hot vaporsuntil serious or irreparable damage results such as by the pistonscoring the cylinder walls and seizing, cracking or other damage causedther by.

The present invention is designed to reliably and dependably protect theengine by stopping the engine. For this purpose, an upright or verticalriser or stand pipe it is attached to the jacket l! through a tappedhole is as by an L-fitting or elbow it coupled or threaded into saidhole and to which the lower end of pipe I4 is coupled or threaded asshown. The riser i2 is spaced far enough away from the cylinder orcylinder head and surrounded by cooler ambient atmospheres so that thewater therein from the cooling water within the jacket surrounding themotor cylinders does not boil. The upper end of the riser or stand pipei l above the normal level of the water of the cooling system thereinadjacent the cylinder head carries an adaptor fitting or nipple E'iinteriorly threaded at both ends and having an intermediate vent hole ittherethrough. The lower end of the nipple ll threads onto the upper endof the riser M as at it and an adaptor or ring nut 22 is threaded intothe upper end of nipple i? as at 26 and has a wrench head 22 on itsupper end interiorly threaded. to take a union plug or nut 23, theexterior threads of which engage or thread into the interiorly threadedupper end of adaptor or ring nut 22 as at 22.

A thermally controlled switch is provided between the riser id at nut 23and the pump or engine control means or ignition circuit thereof to cutofi or ground same and stop the motor should it become overheated suchas from breaking of the fan belt or leakage of cooling water asheretofore pointed out. For this purpose a remote Bourdon tube ortemperature responsive bulb 25 containing a gas or liquid such as methylchloride or other expansible thermal fluid as in connection with myprior Patent No. 2,358,729, dated September 19, 1944, is carried by andextended down through the nut 23 preferably in insulated connectiontherewith, and depends through adaptor or ring nut ill and nipple iibelow the vent ill to dip into the cooling water in the riser or standpipe as at the normal running level thereof in and from the water jacketI! of the engine as indicated at in Figure In effect, a steam pocket ortrap is provided around the tube or bulb 25 by closing the upper end ofthe pipe or housing around the tube formed by the riser i l, nipple iiand nut 726 closed by the nut or plug 23, except for the vent l8.

A conventional or other temperature indicating meter or indicator 25 ismounted on an insulation panel 2! bolted to and insulated from theengine or radiator 13 as seen in Figure 1. A pipe 28 rises from the nutor plug 23 around a terminal conduit or tube 29 extending from the tube25 to the indicator 26 and may be coiled in 4 its length in connectionwith any excess capillary tubing as at 30 and taped if necessary toavoid chafing against any sharp metal surface. Terminal member or tubing29 connects to the indicating meter or guage 25 through the casingthereof which may be metallic and grounded to the ignition circuit ofthe engine including a magneto 3| grounded at 32 through a conduitorWire 33.

The indicator or guage 26, preferably of the liquid type, has its dial34 calibrated or zoned to indicate the thermal condition of thecirculating cooling liquid or water, such as Cold, Run" or Hot or merelythe latter two, and in degrees of temperature in any standard scale,such as 90, 140, 170, and 212 or otherwise, indicating in this instanceas shown, degrees Fahrenheit. A metallic pointer 35 is operativelyconnected or correlated to the remote thermal element 25 of thethermally controlled switch through tubing 2% to move over the dial fromits pivot to indicate the temperature and is grounded through aconductor wire 36 as at 31. The pointer 35 forms a movable contact andis adapted to engage a contact 38 when the cooling medium or water isexcessively hot or above 212 F. and may be of any suitable constructionor type such as'in my prior patent above referred to in which the casing3| has an opening in the wall thereof adjacent said pointer or Hot pointof the dial above 212 F., to receive an internally and externallythreaded sleeve 32 threaded through said opening and the contact 38 isadjustable by its head 40 for regulation of the temperature at which theswitch closes by contact of the pointe1 therewith. The contact 38 maycomprise a screw or threaded shank integral therewith and threadedthrough the sleeve constituting a binding post having a holding nut ornuts ll on the shank bearing against the outer end of the sleeve toconnect a terminal 12 of a conductor wire 43 leading and connected atits opposite terminal 42 to the other side of the electrical powersource or magneto 3i of the ignition circuit of the engine as seen inFigure 4 and to the positive lead or side of the ignition system circuitthrough conductor wire 44 with an interposed ignition or control switch45.

While any thermal controlled switch may be employed and will work inconnection with the control device on the motor as described theadjustable contact as described is preferred to give more minute andaccurate control and to adapt it for different liquid or water cooledengines including especially the vapor cooling system with condensingradiator as described to operate at 212 F. at all times. A conventionalsafety switch arrangement will not operate with such a cooling systembecause failure of the latter due to a broken fan belt of the coolingfan of the radiator or condenser, or leakage of the cooling water willnot raise the temperature above 212 F. as the engine continues to runwith the cylinder wall getting hotter while the water jacket area andwater in the riser I4 gets cooler with lack of vapors until the pistonscores the cylinder walls and seizes causing irreparable damage, orpossible warping or cracking.

With the present safety means or control device and switch the operationis simple, positive and reliable. During the ordinary running, when thetemperature of the cooling medium or water is not excessive and theengine is not excessively hot, the water fills the riser I4 to theoperating level of the engine jacket at 50-11 (Figure 2) and is farenough away from the engine or cylinder or head thereof and surroundedby cooler ambient atmospheres so that the water in the riser does notboil and in efiect serves or acts as a steam trap. Breaking of the fanbelt causes the vapors to crowd in the radiator or condenser faster thanit can condense them and the slight pressure thus caused forces the 212water or higher steam or vapor temperature to seek escape through thevent I8 around the thermal element or Bourdon tube 25 causing the safetyswitch to close by movement of the pointer or movable contact 35 againstthe adjustable contact 38 by the escaping hot water and ground thepointer and ignition circuit of the engine or magneto thereof to cut oilthe ignition system and cause stoppage of the engine thereby preventingany damage thereto. Should the water in the cooling system be lost as byleakage or otherwise dangerously below a safe or normal runnin level,the moment the level falls in the riser connection IS, the steam escapesthrough the riser vent It to expand the thermal fluid or methyl chloridein the element bulb or Bourdon tube 25, swings the pointer to engagecontact 38 and close the switch to ground the magneto or ignitioncircuit at 31 to stop the engine. Filling of the jacket above the propernormal level will cause the excess water to be expelled through theriser vent. The device is simple, inexpensive as well as positive andreliable in operation as it can be depended upon to stop the engineoperation to protect the same from damage. In addition, it can beexpeditiously and economically installed and readily connected forefiective operation.

I do not mean to confine myself to the exact details of constructionherein disclosed but claim all variations falling within the purview ofthe appended claims.

What I claim is:

1. In a safety means for engines having a closed vapor type coolingsystem and ignition means, a thermally controlled means for cutting offthe ignition means when the engine is excessively hot, said meansincluding a source of electrical power for the ignition means, atemperature indicatin guage, a switch forming a part of said guagehaving a movable pointer to indicate the temperature of the coolingliquid and connected to ground, a riser connected at its lower portionto the cooling liquid to receive the same at alevel corresponding tothat in the cooling system and spaced from the engine and exposedexternally to atmospheric air, said riser having a vent near the top, aBourdon tube in the top of said riser and exposed to the liquid therein,the upper end of the riser being closed, and a conduit extending fromthe tube through the riser and connected to the guage to actuate thepointer to close the switch and ground the ignition circuit when thecooling liquid become overheated and tends to escape through the ventwith steam and hot vapors therefrom around the Bourdon tube, to stop theengine.

2. In a safety means for internal combustion engines having a jacket forcooling liquid of a closed vapor type cooling system including acondenser for condensing vapors from the engine jacket, an ignitioncircuit for the engine including a grounded magneto, a temperatureindicator for the cooling liquid including a dial calibrated to indicaterunning temperatures of the liquid, a grounded movable pointer coactingwith said dial, an adjustable contact engageable by the pointer when theliquid temperature is above normal and connected in the ignitioncircuit, a stand pipe having its lower end connected to the jacket toreceive the cooling liquid therefrom at normal running level and spacedfrom said jacket so as to be relatively cool, and a Bourdon tube in thepipe and dipping in the relatively cool liquid therein, a tubing leadingfrom the Bourdon tube to actuate the pointer over the dial according tothe temperature of the liquid, said pipe having a vent above the liquidand being closed elsewhere except where it connects to the jacket,whereby failure of said condenser to condense vapors at the rate atwhich the vapor is produced in the jacket will effect an increase inpressure in said cooling system to cause flow of heated coolant from thejacket to said standpipe to cause the expansible medium in the tube toactuate the pointer as a switch to engage the adjustable contact andclose the ignition circuit therethrough to ground the same and stop theengine.

3. In combination with an internal combustion engine including a closedvapor coolin system having a liquid coolant receiving jacket disposedabout the cylinders thereof, and a condens'ing radiator for condensingthe coolant vapors and returning the condensed vapors to said jacket,and an ignition circuit for said engine including a grounded magneto;safety means comprising a vertically disposed riser spaced from saidjacket, coupling means communicatin the lower end of said riser withsaid jacket substantially below the normal liquid coolant level thereinwhereby said liquid coolant will nornormally seek said level in saidriser, a thermally responsive bulb positioned in the upper end of saidriser and normally submerged in said liquid coolant, a vent opening insaid riser above the normal liquid coolant level therein, normally openswitch means interposed in an electrical conductor extending from saidignition circuit to ground and adapted to be actuated to closed positionby said thermally responsive bulb, and means operatively connecting saidbulb and said switch means whereby the liquid coolant in said riser willnormally have a temperature lower than that of the liquid coolant insaid jacket, and failure of said condenser to condense the coolantvapors at the rate at which the vapor is formed will effect an increaseof pressure within the vapor cooling system causing a flow of the heatedliquid coolant in the jacket into said riser thereby subjecting saidtemperature responsive bulb to increased temperatures for closing saidswitch means to thereby ground said ignition circuit and stop theengine.

FRANK W. MURPHY.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 872,039 Adams Nov. 26, 19071,633,156 Antunes June 21, 1927 2,162,174 Jones June 13, 1939 2,231,845Curran Feb. 11, 1941 2,445,625 Meinholdt July 20, 1948 2,450,630 Bourne,Jr Oct. 5, 1948

